1. Field of the Invention
The present invention relates to a method, the use of the method and an apparatus for decollating blanks of cardboard or the like stacked behind a stop means in a feeding station from a magazine or stack of blanks. The apparatus includes at least one delivery conveyor arranged underneath the stack of blanks, wherein the delivery conveyor includes a conveyor belt and a belt guide means for the controlled removal of the respectively lowermost blank and for conveying the blank to a timed subsequent process with a transfer station.
2. Description of the Related Art
In the field of cardboard processing, particularly the processing of folding boxes, it is frequently required to decollate cardboard blanks of all types from a stack in a machine cycle-dependent manner. In addition to decollating in dependance on a machine cycle, decollating in a manner which is not cycle-dependent is also known in the art.
Decollating in dependance on a machine cycle is always required if the decollating step is followed by processing steps which are carried out in dependence on a cycle. A large number of devices and methods are known in the art for this purpose. Economically useful today are only those devices and methods which ensure a continuous refilling of the stack to be decollated.
However, as compared to decollating which is not dependant on machine cycles, all known methods are at a disadvantage with respect to speed because the means for carrying out decollating in dependance on a machine cycle always requires a certain cyclically returning time.
The following devices and methods are known in the field of decollating cardboard blanks in dependance on a machine cycle and are used today in speed-oriented processing:
(a) Rotary Disk Feeder
Rotary disk feeders have the disadvantage that the decollating element (the upper or carrying rubber element) acts in accordance with the cycle of the machine and, thus, always acts on the blank in accordance with the machine conveyor speed. Moreover, refilling of the magazine poses problems because the blanks must be supplied to the respective end of the stack in a manually prescaled configuration.
(b) Rotary suction feeder
Depending on the embodiment of the rotary suction feeder, the decollating element can be somewhat delayed relative to the machine belt speed. However, the feeder has the disadvantage that the blank to be decollated is always lifted off perpendicularly of the stack and, thus, with increasing speeds the flow of the air between the blank to be delivered at the moment and the residual stack becomes problematic and leads to incorrect feedings.
(c) Timed suction belt feeder
The principle of timed suction belt feeders is used most often in the devices and methods of the above-described type. When using these feeders, decollating speeds of up to 500 cycles per minute are achieved. A disadvantage of these feeders is the fact that the decollating element, i.e., the conveyor belt, acts in accordance with the cycle of the machine and, thus, always acts on the blank in accordance with the machine belt speed. The adjustment of the movement of the timed lifting unit to the respective length of the blanks is also difficult.
The above-described principle is known, for example, from DE 29 46 426 C2 and has up to now made possible the highest speeds of up to 600 blanks per minute. However, the technical requirements for the control of the upward and downward movement of the conveyor belts are substantial.
In contrast to the solutions described above, a relative movement of the stack of the blanks and the conveyor belts is not used in the timed suction belt feeder according to DE 38 11 988 C2. Instead, the feeder belts are driven intermittently. The speed of these feeders is limited because substantial masses must be moved. The technical requirements and the wear of the device are also disadvantages. The system has not been widely accepted in practice.